1. Field of the Invention
This invention relates to a filter holder insertable into the lens barrel of a camera, and a lens barrel having a filter holder positively secured thereto.
2. Description of the Prior Art
Photography is usually carried out with a filter mounted on the picture-taking lens. Several methods of mounting a filter to a picture-taking lens are known. The most widely adopted method involves screwing the filter into the front end of the lens barrel. However, when using a telephoto lens, which usually has a large forward lens element, this method requires a large filter element which is bulky and disadvantageous in terms of ease of handling and manufacturing cost. A second method involves self-contained filters, but this approach limits the available filters to four or five types and requires a complex mechanism to enable selective positioning of the filters. A third method involves screwing the filter into the rear end of the lens barrel, but this requires removal of the lens barrel from the camera body each time the filter is to be changed. A need exists, therefore, for a filter which may be simply attached to lenses having a large forward lens element but which requires only a small diameter filter and which can be positively attached to the camera to prevent the filter from dropping out when the camera is inverted.
It is an object of the present invention to provide a new and improved filter holder which overcomes the deficiencies of the prior art and enables a filter to be positively attached to a lens barrel by a simple operation.